Our material is based on work supported by the National Science
Foundation through NSF-REU grant No. PHY/DMR-1004811.

Dielectric breakdown of nitrogen gas in a microgap (specifically between 10
and 1000 microns) was found to be governed by different mechanisms than breakdown
in large gaps. It is useful to characterize these mechanisms to identify regions
of failure for MEMS (micro-electro-mechanical systems) devices. Pressure dependence
of the breakdown electric field revealed a collisional pressure regime, which
contains particles having frequent low-energy collisions resulting from the
short mean free path of a high pressure gas, and collisionless pressure regime,
which contains particles having infrequent high-energy collisions resulting
from the long mean free path of a low pressure gas. As gap size was reduced,
the collision frequency coefficient was found to depend exponentially on the
pressure exponent. At large gaps (greater than 2540 microns) and at small gaps
(less than 75 microns), the collision frequency coefficient and the pressure
exponent level off, as gap size is varied, showing us that there are different
limiting factors to the diffusion length of the plasma. Optical emissions reveal
that different molecular excitations dominate the plasma at small and large
gaps.
___________________________________________________________________________________________________________________________________________________________ Publications
and Presentations:TJ Klein*, Cameron J. Recknagel*, Christopher J. Ploch*, and S.K. Remillard, "Microwave Breakdown of N2 Gas in a Microgap", Applied Physics Letters, 2011.